1. Field of the Invention
The present invention relates to a semiconductor device including a metallic member a part of which is embedded in a recess formed in a substrate.
2. Description of the Related Art
A semiconductor device including a substrate in which a semiconductor element and a recess are formed and a metallic member embedded in the recess for release of heat has been hitherto known.
Japanese Patent Publication No. 3791459 (hereinafter, Patent Literature 1) discloses a semiconductor device including a semiconductor layer provided with a semiconductor element formed therein, a support substrate formed a plurality of recesses for supporting the semiconductor layer and a metallic member embedded in the recess of the support substrate. The metallic member is made of a material with high thermal conductivity such as copper, aluminum, silver, gold, copper alloy, aluminum alloy, silver alloy, and gold alloy to quickly release heat generated in upper part of the semiconductor element during operation of the semiconductor element.
However, the linear expansion coefficients of copper and aluminum are 17×10−6/° C. and 23×10−6/° C., respectively while the linear expansion coefficient of the support substrate, for example, a silicon substrate is 3×10−6/° C. In the semiconductor device of the aforementioned Patent Literature 1, the metallic member and support substrate are different in linear expansion coefficient. Accordingly, stress due to the difference in linear expansion coefficient affects the support substrate. Furthermore, part of the support substrate where the recess is formed to embed the metallic member therein is thinner than part of the substrate where the recess is not formed. Accordingly, the support substrate warps and deforms.